Crystal Structure and Photoluminescence of Two Terbium Compounds with Bromobenzoic Acid and Phenanthroline.

Two novel Tb(III) ternary complexes, [Tb(Phen)(p-BrBA)] and [TbY(Phen)(p-BrBA)], have been synthesized with p-bromobenzoic acid(p-BrBA) as the primary ligand and 1,10-phenanthroline(Phen) as the secondary ligand. The structures of these complexes are characterized by elemental analysis, IR spectroscopy, UV-vis absorption spectroscopy, thermal analysis (TGA) and single-crystal X-ray diffraction. The crystal structures of the compounds are similar because of similar radii of Tb ion and Y ion. Both the homobimetallic single crystal and the heterobimetallic single crystal belong to the monoclinic system. The results show that both complexes have excellent luminescence properties, including luminescent intensity, luminescent lifetime and quantum yield. The two compounds have an excited state lifetime of milliseconds and the photoluminescence quantum efficiencies of the two terbium complexes can exceed 100% upon excitation to their 5d states in theory, which is attributed to luminescent lifetime and quantum cutting (QC). Furthermore, the luminescent properties of [TbY(Phen)(p-BrBA)] are actually superior to those of [Tb(Phen)(p-BrBA)].